Electrode or terminal for electrolytic apparatus



Sept. 10, 1935. R. D. MERSHON 2,014,005

ELECTRODE OR TERMINAL FOR ELECTROLYTIC APPARATUS I Filed Dec. 19, 1954 s Sheets-Sheet 1 BY C0011 ATTORNEYS Sept. 10, 1935. R. D. MERSHON ELECTRODE OR TERMINAL FOR ELECTROLYTIC APPARATUS Filed Dec. 19, 1934 3 Sheets-Sheet 2 7 u v 0 Z a a I 8 ATTORNEYS Sept. 10, 1935. R. D. MERSHON ELECTRODE OR TERMINAL FOR ELECTROLYTIC APPARATUS 3 ShetS-ShGet- 3 Filed Dec. 19, 1954 INVENTOR Mars/101$ ATTORNEYS Patented Sept. 10, 1935 TROLYTIC APPARATUS Ralph D. Mershon, New York, N. Y.

Application December 19, 1934, Serial No. 758,154

. 18 Claims.

In electrolytic devices such as condensers and rectifiers having filmed electrodes of aluminum or other metal, any filmed part extending out of the electrolyte into the air suffers more or less rapid corrosion at the surface of the electrolyte.

It is therefore customary to submerge the electrodes entirely in the electrolyte; but leads of filming metal coming out of the electrolyte are subject to the attack mentioned and in the course of time must be replaced. In my prior Patent No. 1,572,404 I have described a terminal in which this corrosion" is avoided. For that purpose a body of filming metal is cast or otherwise hermetically secured on the end of an insulating tube or sheath having a vitreous surface, such as a porcelain tube, and a conductor or lead (which need not be of filming metal) is brought out from said body. through the tube. The filming metal on the end of thetube can then be connected to the filmed electrode, so that if the surface of the electrolyte is above the body of filming metal the latter is wholly submerged as well as the electrode to which it is connected and hence neither undergoes corrosion at the surface of the electrolyte. i

The present device is a form of the invention described in my patent referred to above, and has the advantage, among others, that the tube, sheath or like part having a surface of vitreous material can be relatively short and therefore less liable to cracking or breakage" in handling and in assembling. the electrolytic rectifier or condenser, especially when the device is small in diameter, say a quarter or three-eighths of an inch thick. The necessary length to permit the device to extend from a point in the electrolyte,

' and out through the air space above in the vessel or container, is provided by a metallic tubular' a lower surface of vitreous material, to which the electrode metal body is hermetically sealed. With the supporting device in tubular form, the lead or conductor, also preferably of copper, ex-

tends from the filming metal body through the device to the desired point of connection outside the rectifier or condenser.

the filming electrode of a rectifier.

To insure against electrical contact between the metal tube and the conductor or lead the latter may be covered with rubber, or other insulating material, or the interior of the metal tube around. the lead may be filled with an insulating com- 5 pound, or both expedients may be employed. Another advantage of the present construction may be found in the fact that where the metalic tubular part enclosing and projecting the lead is, in electrical connnection with the electrolyte, such 10 part is accordingly at the same potential as the electrolyte,in contradistinction, for example, to a structure wherein filmed active parts extend out past the surface of the electrolyte and in contact with the latter,and such exposed metallic 1 tubular part may in fact conveniently and economically provide a complementary, electrode for the filming metal body, as for instance the nonfilmed electrode when the filming metal body is ratus, in section, incuding a terminal device in elevation; and

Fig. ,8 illustrates another form of the apparatus of Fig. 7, partly in section and partly in elevation. In Fig. 1 the metal tube is shown at ill. Pref- 'erably the tube is of copper, as I have found that not melt or soften at the fusing temperature of the vitreous material, such as the glaze slip on the porcelain part, or the vitreous enamel in other forms. In the form of Fig. 1 the metal tube is tapered on the inside at one end, as indicated, preferably with rather a long taper, conveniently formed by expanding the end of the tube, and an electrode element is fastened thereto, including a porcelain tube II which is tapered to fit snugly in the tapered end of the metal tube. Whether the taper. of the metallic tube is made by expanding the end of the tube or -by reaming or turning the interior, it is sometimes desirable to thin the tapered part or at least its edge portion to lessen any liability of breakage of the porcelain by contraction of the metal tube. Between the two is a layer of a preferably vitreous cementing material indicated at II, with some exaggeration of its thickness. The electrode element also includes, on the protruding end of the porcelain tube, a body or cap of filming metal I3, usually of aluminum or an alloy of aluminum,

in hermetic contact with the porcelain to prevent entrance of electrolyte between the two.

If the filming metal is cast on the porcelain tube or other vitreous-surfaced part, as is the preferred method of obtaining the desired hermetic joint,'a reinforcing member may be employed inside of the filming metal body to resist the compression stresses due to shrinkage of the cast metal in cooling, thus relieving the vitreoussurfaced supporting portion and lessening the tendency to cracking or breakage of the latter by such pressure. In certain of the structures illustrated the reinforcement is shown in the form of a cap at the end of the tubular supporting device. In Figures 1, 2 and 3, this reinforcing part is acap ll composed of iron, steel, invar, or

other metal which has less cooling shrinkage than has the filming metal cast over it. In some cases, as in Figs. 4 and 6, the cap Ila may be of porcelain or lavite, with special advantages as hereinafter described. The feature of a compression :resisting part, howev is not claimed broadly;

herein, but is so claimed inmy Patent No. 1,949,870. Referring again to Fig. 1, conducting lead Ii,

' for connection with the external circuit, extends through the two tubes It and I I and through the reinforcement cap or disk II into electrical con-- 7 nection with the body of filming metal II. The

lead'shown is provided with an insulating covering, indicated at I0.

The form shown in Fig. 2 differs from that of Fig. 1 only in that the end of the porcelain tube in which the body of filming metal is secured is tapered. In Fig. 3 the porcelain tube is untapered at either end. In any of these forms the tube is vitrified throughout or well glazed, so as to have at least a surface of vitreous material; or it should be so vitrified or glazed for the best results, to eliminate all possibility of electrolyte penetrating to the inner surface of the body of filming metal, for the'reason that if such penetration occurs the inner surface of the metal will be filmed in the operation of the apparatus, themetal will be rapidly corroded, and the film is apt to cause the metal to separate from the porcelain. a

In Fig. 4, the metal tube II has an insulating sheath comprisinga thin adherent layer of vitreous enamel II, which is applied as a coating around a lower portion of the tube, usually submerged in the'electroly'te. Around the end of the a coated metallic tube the electrode element, including cap Ila and filming metal body If, can then be secured with outer portions of the tube, above the element, exposed for electrical connection with the electrolyte in the same manner as, for example, in Figs. 1, 2 and 3. The insulating cap Ila is preferably composed of rigid material, such as porcelain, lavite, or the like, and is disposed at the end of the coated tube, as shown. The

filming metal body II is cast around the surface of vitreous enamel II and enclosing cap Ila, while ,lead I! extends from the filming metal, through a suitable aperture in the lavite cap, and out through the tubular metallic part l0, such lead having an insulating cover, of rubber or the like, as at I0. It will be appreciated that the electrode stresses as the filming metal body may set up on the vitreous surface of enamel II, but serves the further important purpose of facilitating insulation of the filming metal fromthe end of the metallic tube, effectively spacing these parts. 1.

In Fig.6, the vitreous enamel coating is carried around the lower end of the metal tube and over another part of its surface at the inside, indicated at 2 la, this-being an effective arrangement for insulating the end of the metal tube I0 in cer- 2 tain cases where an adherent or crack-proof enamel layer can be provided around the extreme end surface of the metal tube. A bushing or like part' 24 of lavite or porcelain can be mounted within the enamelled part of the tube III, as 2 shown, so as to center the lead and to facilitate spacing and thereby insulating the filming metal from the metal tube. The body III of filming metal is readily applied, as by casting-on, in hering metal I! is similarly applied to a surface of 3 vitreous material provided by the enamel coating II at the lower end of metallic tube Ill. Here the lead 25 consists'of a rod which is threaded at its lower end into the filming metal body, at 32, and the interior of tube I0 may be filled with a suitable insulating cement or compound 36, for effective insulation of lead 25. If connection is desired to an anode or other electrode elements within the electrolyte, for example as disclosed in my prior Patent No. 1,572,404, various arrange- 4 ments may be used, preferably such as to make the anode metallically integral with the filming metal body I3. For instance, a lug 21 (shown partly in elevation) may be cast as part of the body I3, and have a vertical slot 28 which receives r a strap 29 consisting of a turned-up integral portion of anode plate 31. The side 38 of the lug is then pinched against the strap and the other ticularly, spacing and insulation of the filming 0 metal from the end of metallic tube I0 is always maintained.

Referring more particularly to the species of the invention shown in Figs. 1, 2 and 3, a preferred method of manufacture is as follows. The 7 part of the porcelain tube II which is to be secured to the metal tube I0 is coated with a vitreous material such as glaze slip, preferably of low fusing point, any of the known low-melting slips used in the ceramic industry being suitable. The

a permanent joint which is preferably hermetic.

ltube," without squeezing too much of the slip outof the joint. This is one reason for tapering the tubes in the manner shown. If both are straight, as in Fig. 3, the metal tube mayslide down too far unless means is provided to prevent it, as by forming a bead H on the inside of the metal tube. Should the weight of the latter tube not be sufficient the desired pressure may be obtained in any other way. One way is to fasten thelead (l5) to the reinforcing disk i4 and run the lead up through the tubes. Then when the slip is melted a pull on the lead will draw the porcelain tube up into the other. For this purpose the lead can be held to the disk l4 in any convenient manner, as by peening'it, or, if the lead is not too thick, by simply knotting it. Or if the lead is thick enough it may be threaded into the disk. The lead may extend out of the furnace through a small hole in the furnace closure, so that when the lead is pulled the copper "tube, butted against the cover, will be firmly held.

It will be observed that as the porcelain tube ing of the same to the metal tube may be effected at the same time. If the tube is already glazed, the coating of slip may be omitted, provided the layer of glaze is thick enough, when melted, to afford the desired hermetic connection with the metal tube. In either case a layer of slip may be applied to the inside of the, metal tube and to the outside of the porcelain tube. In some instances, the porcelain tube can be replaced by a short enamelled metallic tube, the enamel coating being such as to provide the desired hermetic and insulating contact, particularly with the filming metal.

The body or cap of filming metal l3 can in all forms of the invention, be readily formed on the vitreous surface at the end of the tubular supporting device, such as the porcelain tube ll or the enamel layer 2 I. g This can be done by casting in a mold of the desired shape, the disk, cap, or bushing, M, Ma or 24, being held in place by the 1 lead i5. If the device is to be used in a condenser the body of filming metal may be connected to the condenser anode or to the submerged bus by a rod, wire, or strap, also of filming metal, for example as shown in Fig 6 and described hereinabove, and the metal tube may extend out through the cover of the tank containing the electrolyte. With the lead to the body of filming metal insulated from the metal tube. the't'erminal can in many cases be supported in the cover by expanding the tube in the opening through which it extends'or by employing means such as are shown in Figs. 7 and 8, for example when the condenser anodes are mounted in a frame or cage suspended from the cover, as illustrated in my prior Patent No. 1,784,674. In the construction shown in this patent the tank, made of copper, is the cathode of the condenser and is connected to the negative side of the source of exciting voltage. If it is not desired to have the metal tubes carry any current at all they can of course be insulated from,

the tank cover.

The same arrangement as described above for condensers can be used in rectifiers. In some cases, however, the filming metal on the tubular supporting device can itself be a rectifying electrode, especially where the rectifying electrode can be small, for example in a rectifier for exciting an electrolytic condenser in the same electrolyte, as described in my prior Patent No. 1,889,415.

Figs. 7 and 8 illustrate electrolytic apparatus of the condenser and rectifier class, which, including electrode devices of the type described hereinabove, embody the present invention. In Fig. 7 the electrode device is of the species shown in Fig. 1, while in Fig. 8 the device is of the modified form illustrated in Fig. 4. In Fig. 7, 40 represents a wall of a vessel or tank containing an electrolyte M and having a cover 42, parts 40 and 42 being here shown as of metal, preferably copper as herein elsewhere explained relative to the metal surface of the tubular supporting device. The metal tube ID of the electrode device can be expanded in a suitable aperture in cover 42, or it may be provided with screw threads as at 43 and threaded into the metallic cover. Rigidity and security of the connection with the cover can be imparted by soldering the tube and cover as at 44, in Fig. 7, and to this end it is advantageous to employ a soldering metal having a relatively low melting point which, although amply above temperatures attained during formation or'use of the electrolytic device, is such that the metal tube I0 need not be heated in a way that might crack or otherwise impair the porcelain, enamel, glazeslip, or

like material.

In the construction of Fig. 8, the cover plate 42 has a circular recess 45 surrounding the aperture through which the metal tube l0 extends, and a washer 46 of resilient insulating material, such as rubber, Duprene", or the like, is disposed in the recess. A collar 41, having a part which may extend slightly into the recess 45, is then screwed down over the washer 46, compressing the latter into extremely firm grip upon the outer surface of tube Hi. This arrangement provides a firm and liquid-proof seating for the electrode device in the cover; in many cases, the threaded engagement of the tube ill with the cover 42 may be dispensed with, in either the structure of Fig. 7 or that of Fig. ,8.

The tendency of compression stress exerted by casting H. to crack or break the vitreous-surfaced material H or H of the tubular supporting device can also be lessened by using a relatively soft metal for the casting, such as pure aluminum. When the device is to be used to connect a condenser anode with the external circuit pure aluminum is desirable, but when the metal body is to be a rectifying electrode an aluminum alloy is usually better from the electrical standpoint. In many cases it is also advantageous, for example when a porcelain tube is included, to use a tapered tube and have the casting terminate at the line of greatest diameter, as in Figs. 1 and 2, for example, since it has been found that in this construction the breakage tendency is decreased.

As stated above it is in all devices highly desirable to have the joints between the electrode element or filming metal body and the vitreous material perfectly hermetic, to eliminate all possibility of electrolyte penetrating into such joints. In the case of the filming metal, this hermetic relation is best attained by casting the metal on the supporting device, but with care it is'possible of attainment by accurately fitting on the vitreous surface of the device a pre-cast or otherwise preformed body of filming metal, shrinking it on the device if desired. In either case, especially if the part to be shrunk on the tubular device is a casting, it is desirable to soften the metal as much as possible by annealing.

This application is in part a continuation of my copending application Serial No. 710,058, filed February '7, 1934, for Terminal devices for electrolytic condensers and rectifiers."

' It is to be understood that the invention is not limited to the specific embodiments herein described but can be embodied in other forms without departure from its spirit.

I claim:

1. Electrolytic apparatus of the condenser and rectifier class, having an electrolyte, a metal containing vessel therefor having a cover, and an electrode device extending into the electrolyte, comprising a filming metal body completely submerged in the electrolyte, a lead connected to said filming metal body and extending out of the apparatus, and a tubular device adapted 'to protect the lead to said filming metal from access of electrolyte, said tubular device including a metal tube extending from the cover into the electrolyte and in electrical contact with the latter, and said tubular device having at its lower part a surface portion of vitreous material, and said filming metal body being secured to the tubular device in hermetic contact with the surface of vitreous material and being thereby insulated from direct electrical connection with the metaltube.

2. An electrode device for an electrolytic condenser or rectifier, comprising a filming metal body adaptedto be completely submerged in an electrolyte, a lead connected to said body and extending out of the electrolyte, and a tubular device disposed around the lead and having an external surface which with the filming metal body provides an hermetic seal against access of electrolyte to the lead at the point of emergence of the latter and which, being adapted to extend within the rectifier or condenser, is metallic for a substantial portion of its length and is of vitreous material at another portion within the electrolyte when the electrode device is inserted in the latter, said filming metal body being secured to the tubular device in hermetic contact with the surfaceof vitreous material, and being thereby insulated from direct electrical connection with the aforesaid metallic portion.

3. Electrolytic apparatus of the condenser and rectifier class, having an electrolyte, and an electrode device extending into theelectrolyte, comprising a metallic supporting member, an electrode element including a body of filming metal,

and means securing the electrode element to the metallic supporting member with the filming metal insulated from direct electrical connection with said metallic supporting member, said means comprising a thin adherent layer of vitreous material located at a part of the metallic supporting member nearest the electrode element, with outer portions of the supporting member surface free of said vitreous material, said layer ,tached, and wherein the electrode element sur face to which the vitreous layer adheres is a surface of said porcelain member.

5. The electrolytic apparatus of claim 3 wherein the layer of vitreous material comprises a coating of vitreous enamel around an end portion of the metallic supporting member, and wherein the electrode element surface in adherence with the vitreous layer is provided by the filming metal body cast around and against the enamel coating and hermetically sealing the end of the supporting member.

6. An electrode device for an electrolytic condenser or rectifier, comprising a metal tube adapted to extend into the condenser or rectifier, an electrode element including a body of filming metal, a lead electrically connected to the body of filming metal and extending therefrom through the metal tube, and means securing the electrode element to the end of the metal tube with the filming metal insulated from direct electrical connection with the tube, whereby the lead is hermetically sealed against access thereto by the electrolyte in which the electrode device is immersed, said means comprising a thin adherent layer of vitreous material located at a part of said metal tube near its end, with outer portions of the tube surface free of said vitreous material, said layer of vitreous material being disposed intermediate the metal tube and an adjacent surface of the electrode element, and adhering to the tube and the said surface of the electrode element.

'7. In an electrode device for an electrolytic condenser or rectifier, a metal tube adapted to extend'into the condenser or rectifier, a porcelain tube extending into an end of the metal tube and hermetically sealed thereto, and a body of filming metal on the porcelain tube, hermetically sealing the outer end of the same and spaced from the metal tube so as to be insulated therefrom.

8. An electrode device for an electrolytic condenser or rectifier, comprising a metal tube adapted to extend into the condenser or rectifier.

a porclain tube having a vitreous surface, ex-.

tending into an end of the metal tube and hermetically sealed thereto by a layer of glaze, a body of filming metal on the porcelain tube, hermetically sealing the outer end of the same and spaced from the metal tube so as to be insulated therefrom, and a conducting lead electrically connected to the body of filming metal and extending therefrom through said tubes. I

9. A device for the purpose described, comprising a metal tube having an end tapered inside. a tapered porcelain tube fitted in the tapered end of the metal tube and hermetically sealed thereto by an interposed layer of glaze, a body of filming metal cast over the outer end of the porcelain tube and spaced from the metal tube so as to 'be insulated therefrom, and a conducting lead prising a metal tube having an end inwardly tapered inside, a tapered porcelain tube fitted 75 intothe tapered end of the metal tube and hermetically sealed thereto, the taper on the porcelain tube beginning outside'of the metal tube at a point spaced from the edge of the latter, and a'body of filming metal cast in theformof a cap over the end of the porcelain. tube and hermetically sealed thereto by an interposed layer of glaze, the edge bf the cap terminating substantially at the beginning of the said taper on the porcelain tube.

11. A'device for the purposedescribedrcomprising a metal tube having an end inwardly taperedinslde, a tapered porcelain tube fitted into the tapered end of the metal tube and hermetically sealedthereto, the outer portion of the:

porcelain tube tapering also toward its outer end from a point spaced from the edge of the metal tube, and a cap of filming metal cast on the porcelain tube with its edge terminating substantially at the juncture of the two tapers on the porcelain tube.

, to be insulated therefrom, and a conducting lead electrically connected to the body of filming metal and extending therefrom through said tubes.

' 13. In a device for the purpose described, a metal tube having an end tapered inside, a

tapered porcelain tube fitted in the tapered end or the metal tube and hermetically sealed thereto by an interposed layer of glaze solidified from 1 "fusion between the tubes, and the metal tube be- 7 ing in tension on the solidified glazejand a body of filming metal cast over the outer end .of the porcelain tube and spaced from the metal tube so as to be insulated therefrom.

-l4. An electrolytic apparatus of the condenser and rectifier class, having an electrolyte, and a terminal device'comprising a metal tube extendinginto the electrolyte from. outside or the same and having on its submerged portion a coating or enamel, and body of filming metalcarried by the said submerged portion of the metal tube and insulated from direct electrical connection therewith by-the enamel, the filming metal hermetical .lyfitting the enamel and the metal tube being I .in electrical connection with the electrolyte.

15; Electrolytic apparatus of the condenser and rectifier class, having an electrolyte, and an electrode device extending intothe electrolyte, comprising a metallic-member coated, with a thin adherent layer of enamel-and having a supporting portion extending; through and out of the electrolyte which is free of said enamel coating and which iselectricallyconnectedwith the elec- .,trolyte, and a body of-filming metal secured to the enamelled member and hermetically fitting the enamel thereon, said body of filming metal being thereby insulated from direct electrical connection with said metallic member.

\ 16. An electrode device {or an electrolytic condenser or rectifier, including a metallic member having a thin adherent enamel coating providing an insulating sheath therefor, and a metal electrode member-surrounding the first-mentioned coated member and gripping the enamel coating 10 -with.hermetic contact, said electrode member.

enclosing an end of the enamelled metallic member and being insulated from direct electrical connection with the metallic-member, and said device also including means comprising a rigid 15 insulating part extending within the electrode.

memb'erfor resisting and reducing compression stresses exerted by saidelectrode member on the enamel coating, said'part being disposed adjacent the endof the metallic member for facilitating 20' insulationof the electrode member from said end.

1'1. Electrolytic apparatus of the condenser and rectifier class, having an electrolyte, and having extending into the electrolyte an electrode and terminaldevice for sealing the lead of the elec- 25 trode of'the same against access thereto by the electrolyte in which the electrode is immersed,

said device including a tubular metallic member having a thin insulating sheath surrounding and closely fitting the member for direct reinforcement thereby, said sheath comprising an adher ent coating of enamel, and a body of electrode metal secured to the sheathed member in' hermetic contact with the sheath and enclosing the endof the member and insulated from direct 86 electrical connection with the metal of said mem- -ber, said terminal device also including, a lead connected to the electrode metal body and disposed within and insulated from the sheathed member, said. electrode metal .body and said 40" sheath providing a sealed electrolyte-proof surface for the terminal device, when the latter is inserted in the electrolyte, whereby access of electrolyte to the lead is. prevented, and said tubular metallic member having a supporting 45 portiontherefor, remote from its aforesaid end, which is in direct'electrical contact with the electrolyte. V

18. A terminal device for an electrolytic "cons denser or rectifier, comprising a metallic tubular 50 *member having an adherent coating of enamel around a portion adjacent its end. a lead extending through the tubular member-mud insulated theretrom, and an electrode element secured to the enamelled tubular member, said element in- 66 .cluding a'body of filming metal gripping the enamelcoating' withhermetic contact, said film- I ing metal-being electrically connected with the lead and being insulated from direct electrical connection with the metallic tubular member,

andsaid element also including an insulating part enclosed within thefilming metal bodyand spacing and insulating the filming metal from the end of the metallictubular member.

H smasnom es RALPH n. 

